<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>Title</title>
    
    <style>
      .card {
        border: 1px gray solid;
        border-radius: 10px;
        padding: 15px;
      }
      
      .card-title {
        font-size: 15px;
        font-weight: bold;
        margin: 10px;
      }
      
      .card-body > div {
        color: darkgray;
        background: pink;
        margin: 10px;
        width: 100px;
        height: 100px;
      }
    </style>
  </head>
  <body>
    <!--display属性值为flex时外部显示类型为弹性盒子，弹性盒子指横向或纵向的一维页面布局-->
    <div class="card">
      <div class="card-title">正常布局流</div>
      <div class="card-body">
        <div>1</div>
        <div>2</div>
        <div>3</div>
      </div>
    </div>
    <br>
    <div class="card">
      <div class="card-title">弹性布局</div>
      <div class="card-body" style="display: flex">
        <div>1</div>
        <div>2</div>
        <div>3</div>
      </div>
    </div>
  </body>
</html>